Mass spectrometric proteome analysis for profiling temperature-dependent changes of protein expression in wild-type Caenorhabditis elegans

We investigated the effect of cultivation temperatures on the protein expression levels in the fourth larval stage of the postembryonic development of wild-type Caenorhabditis elegans by mass spectrometric proteome analysis. From the 64 protein spots that were investigated, 5 spots were found reproducibly differently expressed when proteome maps derived from animals kept at 15degreesC and at 25degreesC, respectively, were compared. Spots of heat shock proteins HSP 70 (CE18679 or CE09682) and HSP 16 (CE1 4249) were present only in gels from protein extracts when worms were grown at 15degreesC. Spots of two metabolic enzymes, the isocitrate dehydrogenase (CE1 0345) and the aspartic proteinase (CE21681) were detected only in cultures grown at the lower temperature as well. A protein with still unknown function (CE05036) was present only in gels from worm samples grown at 25degreesC. We show for the first time by proteome analyses that cultivation of worms at the lowest temperature of the known physiological range (15degreesC) already triggers a (weak) stress response in wild-type animals. This work led to the identification of internal control proteins in the wild-type strain for further characterization of temperature-sensitive strains using a proteomics approach.